Measurements & Conversions

Unit conversion sounds like the one place errors cannot hide, and it is where several of the most expensive ones happen. Weight and volume are not interchangeable without a density, a US gallon is not an imperial gallon, and a ton means three different masses depending on who is speaking. The conversions here are exact where an exact definition exists and state their assumption where one does not.

Material conversions — cubic yards to tons, bags to volume — depend on a density that varies with moisture, compaction and grading. Those pages name the density they use and let you change it, because a damp aggregate and a dry one differ by enough to change a delivery. An exact-looking answer built on an assumed density is precision without accuracy.